Vegan vs Paleo primal low carb diet for cyclists weight loss?

Some people out there say that steak helps keep you lean. They usually weigh 300lbs and don't know much about watts per kg. Then you have guys like Lance and Cadel that use vegan diets during the year to 'drop weight' for the mountains.

I did youtube vid to clarify what various authors look like after years following their dietary recommendations.

Wow ...that's incredible timely for me. I had been as close to 100% paleo as one can get for most of the year ...until I went of on a high adventure Boy Scout trip for a weak where it simply was not practical to maintain the paleo diet. I was getting into the primal lifestyle however. Anyway, I was thinking I would like to experiment with something else now that the *instant* food experiment with the Boy Scouts is over.

BTW --not sure if there is a correlation but it seems that eating grains for the first time in months gave me a slight headache for a few days.